DIGESTIVE SYSTEM

• It is a long, continuous tube that connects the mouth with the anus. It includes the mouth, pharynx, esophagus, stomach, and small and large intestines.

  Gastrointestinal (GI) Tract
• The walls of the organs of the GI tract consist of four different tissue layers:

  1. Mucosa
  2. Submucosa
  3. Muscularis Externa
  4. Serosa
• It is the innermost layer surrounding the lumen, or open space within the organs of the GI tract. This layer consists mainly of the epithelium with the capacity to secrete and absorb substances.

  Mucosa
• This layer consists of connective tissue that contains blood and lymph vessels and also nerves. The vessels are needed to absorb and carry away nutrients after food is digested, and nerves help control the muscles of the GI tract organs.

  Submucosa
• This layer contains two types of smooth muscle: longitudinal muscle and circular muscle. The longitudinal muscle runs the length of the GI tract organs and circular muscle encircles the organs. Both types of muscles contract to keep food moving through the track by the process of peristalsis.

  Muscularis Externa
• It is the outermost layer of the walls of GI tract organs. It is a thin layer that consists of connective tissue and separates the organs from surrounding cavities and tissues.

  Serosa
• The small intestine is made up of three parts:

  1. Duodenum
  2. Jejunum
  3. Ileum
• It is a narrow but very long tubular organ. It is the site of most chemical digestion and virtually all absorption of nutrients.

  Small Intestine
• It is the first part of the small intestine. It is also the shortest part. This is where most chemical digestion takes place.

  Duodenum
• It is the second part of the small intestine. This is where most nutrients are absorbed into the blood.

  Jejunum
• It is the last part of the small intestine. A few remaining nutrients are absorbed in this part, and from this part, any remaining food waste passes into the large intestine.

  Ileum
• It is another tubular organ like the small intestine, but it is wider and shorter than the small intestine. It connects the small intestine and the anus. Waste that enters in this organ is in a liquid state.

  Large Intestine
• It is the first digestive organ that food enters.

  Mouth
• This digestive organ begins the mechanical digestion of food.

  Mouth
• It is a long, narrow tube that carries food from the pharynx to stomach. It is located in the throat near the trachea (windpipe), and receives food from your mouth when you swallow.

  Esophagus
• It is a hollow organ, or container, that holds food while it is being mixed with stomach enzymes. These enzymes continue the process of breaking down food into a usable form.

  Stomach
• It is a food that enters the small intestine from the stomach which is in the form of a thick slurry (semi-liquid).

  Chyme
• This digestive organ is a long, flat gland that lies in the abdomen behind the stomach. It produces enzymes that are released into the small intestine to help with digestion.

  Pancreas
• It is a digestive organ with its main digestive function is to produce and secrete a fluid called "bile," which reaches the small intestine through a duct.

  Liver
• It is a small sac below that liver that stores some of the bile from the liver. It also concentrates the bile by removing some of the water from it. It then secretes the concentrated bile into the small intestine as needed for far digestion following a meal.

  Gallbladder
• This digestive organ secretes many digestive enzymes and releases them into the small intestine for the chemical digestion of carbohydrates, proteins, and lipids. It also helps to lessen the acidity of the small intestine.

  Pancreas
• It is a sac-like organ of the digestive system between the esophagus and small intestine in which both mechanical and chemical digestion takes place.

  Stomach
• The esophagus is part of the upper GI tract.

  True
• It is a long, narrow tube-like organ of the digestive system where most chemical digestion of food and virtually all absorption of nutrients take place.

  Small Intestine